Mack 470 etech fuel return

[Will]

Gday

The fuel return comes out under number 4 eup. There is a big line going back to the fuel tank, then there is a 1/4” line come from the front head going back down to the bigger return line. 
 

what does this 1/4” line do and is fuel meant to be coming out of it or does it push fuel back up into the head? 
 

thanks 

[Joey Mack]

That is a return for the injectors. 

[Will]

Does much fuel come out of that line mate?

[Joey Mack]

Yes.  

[Will]

There is no fuel coming from that line, what could be the problem? 

[Mackpro]

Have the injectors been changed recently? If so, possibly the incorrect ones were installed. Only the first few years of the ETECH style engines had the injector fuel return system in the cylinder heads that went to the fuel pressure regulator via plastic push on fuel return hose. Here in the US the year model range was about 1998.5 to 2001.5 . Then the CCRS and ASET family of engines came out and all used the “leakless” injectors which did not have the plastic fuel return line coming off the cylinder head. A lot of the newer cylinder head casting still had the passage ways in the heads for fuel return system but had pipe plugs in them to block them off. Also the ETECHs with the fuel return in the cylinder heads need 2 O-rings on each injector. The “ leakless “ injectors only need the top O-ring.